Systems for driving the generation of products using quantum vacuum fluctuations

ABSTRACT

Described herein are systems incorporating a Casimir cavity, such as an optical Casimir cavity or a plasmon Casimir cavity. The Casimir cavity modifies the zero-point energy density therein as compared to outside of the Casimir cavity. The Casimir cavities are paired in the disclosed systems with product generating devices and the difference in zero-point energy densities is used to directly drive the generation of products, such as chemical reaction products or emitted light.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent Ser. No. 16/870,860,filed on May 8, 2020, which is a continuation-in-part of U.S. patentapplication Ser. Nos. 16/855,890, 16/855,892, and 16/855,897, all filedon Apr. 22, 2020, and claims the benefit of and priority to U.S.Provisional Application No. 62/904,666, filed on Sep. 23, 2019. Theseapplications are hereby incorporated by reference in their entireties.

FIELD

This invention is in the field of devices. This invention relatesgenerally to quantum devices for generating products such as fuel andlight.

BACKGROUND

According to quantum theory the quantum vacuum is filled withelectromagnetic radiation in the form of quantum vacuum fluctuations.There has been substantial discussion about whether this energy can beharvested, and if so, how. A chief problem in harvesting this energy isthat it forms the energy ground state, and so it does not flow from oneregion to another. However, the quantum vacuum energy isgeometry-dependent, and its density is lower in a Casimir cavity thanoutside of a Casimir cavity. The use of Casimir cavities therefore opensthe possibility of making use of the quantum vacuum fluctuations todrive energy from one location to another.

SUMMARY

Devices for generation of products, such as fuel and light, aredescribed herein. In embodiments, devices described herein use twodifferent regions in which the energy density of the quantum vacuum isdifferent to drive energy through a device such that a portion of theenergy can be captured and/or used directly for driving a chemicalreaction or in a process of generating light.

In an aspect, systems are disclosed for generation and capture of chargecarriers that are excited by quantum vacuum fluctuations. Systems ofthis aspect may use an asymmetry in quantum vacuum fluctuations withrespect to a device, such as a product generating device, to drive aflow of energy or particles or waves through the device for use ingenerating products, such as fuel or light. Systems of this aspect mayalso or alternatively comprise a product generating device having astructure permitting fast transport and/or capture of a charge carrierexcited by quantum vacuum fluctuations. In some embodiments, a system ofthis aspect may include a Casimir photocatalyzer or a Casimir lightsource.

An example system of this aspect may comprise a product generatingdevice and a zero-point-energy-density-reducing structure adjoining thedevice. In embodiments, the zero-point-energy-density-reducing structureprovides an asymmetry with respect to the device that drives a flow ofenergy or particles or waves across the device. The devices disclosedherein are distinguished from photoelectrolysis systems, or devices thatmake use of light from an externally applied voltage or current, orlight source in the case of photoelectrolysis, to generate products suchas fuel or light and are capable of producing a flow of energy orparticles or waves that occurs even in the absence of external sourcesof illumination or power. Stated another way, the disclosed devices arecapable of producing fuel or light whether in dark conditions or inlight conditions and whether a voltage or current is provided by anexternal source or not.

The asymmetry noted above may produce a voltage difference between afirst region of the product generating device and a second region of theproduct generating device. The asymmetry may produce a net charge flowbetween a first region of the product generating device and a secondregion of the product generating device. The asymmetry may provide areduction in a zero-point energy density on a first side of the productgenerating device as compared to the zero-point energy density on thefirst side of the product generating device in an absence of thezero-point-energy-density-reducing structure. The asymmetry may providea difference between a first zero-point energy density on a first sideof the product generating device and a second zero-point energy densityon a second side of the product generating device, such that thedifference drives a flow of energy through the product generatingdevice.

At least a portion of the flow of energy is used in the systems of thisaspect by the product generating device, such as to generate light orproduce fuel. In contrast to conventional light-emitting devices andphotocatalysis, electrochemical photolysis, and photoelectrolysissystems used for fuel production, the flow of energy occurs even in anabsence of application of voltage or current to the product generatingdevice from an external source and/or in an absence of external sourcesof illumination.

Example zero-point-energy-density-reducing structures useful with thesystems of this aspect include Casimir cavities. For example, thezero-point-energy-density-reducing structure may comprise an opticalCasimir cavity or a plasmon Casimir cavity.

In cases where the desired products of the systems of this aspect are afuel, the product generating device comprises a chemical reactiondevice, in which reaction products are generated by the flow of energy.Optionally, the product generating device comprises an electrolysisdevice or a photocatalysis device. An example chemical reaction devicecomprises a first electrode adjoining thezero-point-energy-density-reducing structure; a second electrode inelectrical communication with the first electrode; and an electrolytebetween the first electrode and the second electrode. Such aconfiguration may be operable for electrolysis of water.

In cases where the desired products of the systems of the aspect arelight, the product generating device comprises a light emission device,in which the flow of energy induces direct generation of light. Anexample, light emission device may comprise a phosphor positionedadjacent to the zero-point-energy-density-reducing structure, so as toprovide a cathodoluminescent structure. Other useful light emissiondevices include those comprising a plasmon-driven light emission device,or a structure exhibiting a negative differential resistance.

Without wishing to be bound by any particular theory, there can bediscussion herein of beliefs or understandings of underlying principlesrelating to the invention. It is recognized that regardless of theultimate correctness of any mechanistic explanation or hypothesis, anembodiment of the invention can nonetheless be operative and useful.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 provides a plot showing energy density spectra for quantum vacuumradiation and blackbody radiation.

FIG. 2 provides a schematic illustration of an example device driven byan energy density difference, in accordance with some embodiments.

FIG. 3 provides a schematic illustration of an example system driven byan energy density difference, in accordance with some embodiments.

FIG. 4 provides a cross-sectional illustration of an example Casimircavity adjacent to an example device, in accordance with someembodiments.

FIG. 5 provides a cross-sectional illustration of an example Casimirphotoinjector, in accordance with some embodiments.

FIG. 6 provides a cross-sectional illustration of an example plasmonCasimir cavity, in accordance with some embodiments.

FIG. 7 provides a cross-sectional illustration of an example plasmoninjector device, in accordance with some embodiments.

FIG. 8 provides a cross-sectional illustration of an example Casimirphotocatalyzer, in accordance with some embodiments.

FIG. 9A, FIG. 9B, and FIG. 9C provide cross-sectional illustration ofexample Casimir light sources, in accordance with some embodiments.

FIG. 10A provides a layout of patterns for fabricating an exampleCasimir cathodoluminescence system, in accordance with at least someembodiments.

FIG. 10B provides a cross-sectional illustration of an example Casimircathodoluminescence system, in accordance with at least someembodiments.

DETAILED DESCRIPTION

Quantum vacuum fluctuations fill all space with electromagneticradiation. The energy density of this radiation in free space is

$\begin{matrix}{{\rho({hf})} = {\frac{8\pi f^{2}}{c^{3}}\left( {\frac{hf}{{\exp\left( {{hf}/{kT}} \right)} - 1} + \frac{hf}{2}} \right)}} & {{Eq}.1}\end{matrix}$

where his Planck's constant, f is the frequency of the radiation, c isthe speed of light, k is Boltzmann's constant, and T is the temperature.The first term in brackets in Eq. 1 is due to thermal blackbodyradiation at non-zero temperatures, and the second term is temperatureindependent and corresponds to the quantum vacuum radiation.

The energy density (p(hf)) spectrum for both the temperature dependentterm and the temperature independent term in Eq. 1 is shown in FIG. 1,where the data is plotted as a function of photon energy, hf, where h isPlanck's constant and f is optical frequency, which varies with thereciprocal of the wavelength. At 300 K, the thermal component (labeledBlackbody(hf) in FIG. 1) reaches its maximum in the infrared throughvisible parts of the spectrum, whereas the quantum vacuum radiation(labeled QVR(hf) in FIG. 1) component grows with the frequency cubed andbecomes much larger than the thermal component of the spectrum atvisible light frequencies and beyond (as shown in Eq. 1, above, and Eq.2, below). For 300 K blackbody radiation, the quantum vacuum radiationcomponent exceeds the thermal part for any frequencies above 7 THz,corresponding to a photon energy of approximately 29 meV. Because theenergy density of the quantum vacuum radiation part of the spectrum athigh frequencies is much larger than that of the thermal spectrum, muchmore power may be available from the quantum vacuum radiation.

Harvesting and using energy arising out of the quantum vacuum radiationdoes not appear to violate any physical laws, but because the energycorresponds to that of the ground-state, there is generally no driverfor the energy to flow. However, the quantum vacuum radiation isgeometry dependent, and its density can be different in differentregions of space. For example, a zero-point-energy-density-reducingstructure can establish a geometric condition where the quantum vacuumradiation density in one region of space can be lower than in freespace, such as outside the structure, which, therefore, provides acondition for energy flow to occur. One approach is described in U.S.Pat. No. 7,379,286, which is hereby incorporated by reference.

One example of a zero-point-energy-density-reducing structure is aCasimir cavity. As used herein, the term Casimir cavity includes bothoptical Casimir cavities and plasmon Casimir cavities, both of which aredescribed in detail below. As a brief introduction, an optical Casimircavity can be formed using two closely-spaced, parallel reflectingplates. As a result of the requirement that the tangential electricfield must vanish (for an ideal reflector) at the boundaries, limits areplaced on which quantum vacuum modes (i.e., field patterns) are allowedbetween the plates. In general, the modes allowed include those wherethe gap spacing is equal to an integer multiple of half of thewavelength. Modes having wavelengths longer than twice the gap spacingare largely excluded. This results in the full spectrum of quantumvacuum modes exterior to the plates, described by Eq. 1, being largerand more numerous than the constrained set of modes in the interior, andthus there is a lower energy density in the interior. The criticaldimension, which determines the wavelength above which quantum vacuummodes are suppressed, is the gap spacing (for the case of a onedimensional optical Casimir cavity). Optical Casimir cavities can alsobe constructed in the form of cylinders (nanopores), in which case thecritical dimension is the diameter. Optical Casimir cavities may beformed having other geometries as well, which can be used with thedisclosed devices. Aspects described herein make use of the fact thatthe quantum vacuum energy level is dependent upon the local geometry,specifically the presence of a zero-point-energy-density-reducingstructure, like a Casimir cavity.

Zero-point energy is the ground state energy of a system that remainseven at zero temperature. Quantum vacuum fluctuations include zero-pointenergy fluctuations in the form of electromagnetic radiation. Quantumvacuum radiation is one type of zero-point energy that exists in freespace and transparent media. Zero-point energy-driven modes exist inmedia beside free space, and in waves besides electromagnetic waves.Other waves include phonons, polaritons including plasmons, plasmaoscillations, and electromagnetic waves in matter, spin waves, andacoustic waves. Only high frequency waves that carry sufficient energyare of interest for harvesting, similar to the condition for quantumvacuum radiation shown in FIG. 1. For each of these waves supportingzero-point energy-driven modes, the energy can be extracted if a spatialgradient in the zero-point energy magnitude can be provided, similar tothe way an optical Casimir cavity can create a spatial difference inzero-point energy densities in the form of quantum vacuum radiation.

Plasmons are charge oscillations and include surface plasmons and volumeor bulk plasmons. Surface plasmons can exist at interfaces betweenconductors, plasmas, or charged gases, and dielectrics, such asinsulators, semiconductors, and air. Bulk or volume plasmons arelongitudinal charge oscillations inside conductors, plasmas, or chargedgases, and generally have a higher energy and frequency than surfaceplasmons. The term plasmon is used herein to refer to both surface andbulk plasmons, and other infrared through ultraviolet light frequencypolaritons in materials. Plasmons in conductors, including metals, or atconductor interfaces can support waves having frequencies of interest,and therefore cavities that suppress a range of plasmon modes canprovide the sort of asymmetry needed for zero-point energy harvestingand can be used as zero-point-energy-density reducing structures. Thesestructures are referred to herein as plasmon Casimir cavities and aredescribed in further detail later.

To be able to make use of a difference in zero-point energy densities,an asymmetry with respect to a zero-point-energy-density-reducingstructure may be used, allowing a portion of the energy to be harvested.FIG. 2 shows an example arrangement, where azero-point-energy-density-reducing structure 200 can be used toestablish an asymmetry in zero-point energy densities between one sideof a transport medium 250 and the other, such as by having one side ofthe transport medium 250 face the zero-point-energy-density-reducingstructure 200, for example. By using a structure for producing anasymmetry in the zero-point energy density on one side of the devicewith respect to the other, and a structure for transport (e.g., thetransport medium 250) of the excited charge away from the excitationlocation, a net power across the transport medium from the side that hasno zero-point-energy-density-reducing structure, and hence has a higherzero-point energy level, to the side with thezero-point-energy-density-reducing structure, which has a lowerzero-point energy density, can flow across the transport medium 250, asschematically shown by arrow 255. The same concept applies if both sideshave zero-point-energy-density-reducing structures, but having differentcritical dimensions or frequency cutoffs.

In the above description of a zero-point-energy-density-reducingstructure depicted in FIG. 2, the energy is shown to travel from oneside of a transport medium to the other. This flow of energy can be usedin a system for directly generating products, such as light or chemicalor electrochemical reaction products, by coupling a product generatingdevice adjacent to or adjoining a zero-point-energy-density-reducingstructure. FIG. 3 shows an example arrangement for such a system, wherea zero-point-energy-density-reducing structure 300 is adjacent to afirst device component 325 but not adjacent to a second device component330, establishing an asymmetry in zero-point energy densities betweenthem. A transport medium 350 is positioned between the first devicecomponent 325 and the second device component 330. First devicecomponent 325, second device component 330, and transport medium 350 canbe components of a product generating device. In FIG. 3, first devicecomponent 325 is adjacent to, and energetically constrained by, thezero-point-energy-density-reducing structure 300, while the seconddevice component 330 is unconstrained by thezero-point-energy-density-reducing structure 300. By using a structurefor producing an asymmetry in the zero-point energy density at the firstdevice component 325 with respect to the second device component 330,and a structure for transport (e.g., the transport medium 350) of energyor waves or charge, a net power can flow from the device secondcomponent 330 that has no zero-point-energy-density-reducing structure,and hence has a higher zero-point energy level, to the first devicecomponent 325 adjacent to the zero-point-energy-density-reducingstructure 300, which has a lower zero point energy density, driving thegeneration of products. For example, if the first device component 325,the second device component 330, and the transport medium 350 areconstructed appropriately, the flow of energy can be used to directlydrive oxidation and/or reduction reactions without actually having toharvest the energy as an electrical voltage and/or current, and candirectly produce chemical fuel. An electrical lead 395 can be connectedbetween the first device component 325 and the second device component330, providing a return path for current to flow as the oxidation and/orreduction reactions occur. As another example, the flow of energy can beused to directly cause emission of light, such as where the flow ofenergy causes electrons to interact with a phosphor, again withoutactually having to harvest the energy as an electrical voltage and/orcurrent.

Another way to characterize an asymmetry requirement is in terms ofequilibrium and detailed balance. In equilibrium, the flow of energyfrom any first element to any second element must be balanced by anequal energy flow from the second element to the first element. Thisresults from a detailed balance. A zero-point-energy-density-reducingstructure can facilitate a means to break this balance, so that there isa smaller flow of energy from the side of a device with thezero-point-energy-density-reducing structure than from the side of adevice without it.

Optical Casimir cavities. FIG. 4 provides an illustration of an exampleof an optical Casimir cavity 400 adjacent to a transport medium 450,which may comprise or correspond to a portion of a product generatingdevice, for example. Optical Casimir cavity 400 comprises a firstreflector 405, a second reflector 410, and a gap 415 between the firstreflector 405 and the second reflector 410. Gap 415 (also referred toherein as a cavity layer) may be an empty gap (e.g., evacuated orcorresponding to a vacuum) or filled with a gas, which may be achievedwith rigid substrates and spacers. In some embodiments, gap 415 may befilled with a material 416, such an at least partially transparentoptical material for at least some wavelengths of electromagneticradiation supported by the optical Casimir cavity, preferably the entirevisible range through the near ultraviolet. In contrast with a gas,material 416 may comprise a condensed-phase material, such as a solid,liquid, or liquid crystal. Example materials useful as a cavity layerinclude, but are not limited to, silicon oxide or aluminum oxide.Alternatively, it may be sufficient or desirable to fill the gap with apolymer such as PMMA (polymethyl methacrylate), polyimide, polymethylmethacrylate, or silicone, which can provide adequate transparency atwavelengths of interest. In some examples, the material of a cavitylayer, such as those materials described above, may have a transmittanceof greater than 20% for at least some wavelengths of electromagneticradiation from 100 nm to 10 μm. Advantageously, the material of a cavitylayer may have a transmittance of greater than 50% for at least somewavelengths of electromagnetic radiation from 100 nm to 10 μm. In somecases, the material of the cavity layer, including at least some of thematerials described above, may have a transmittance of greater than 70%or greater than 90% for at least some wavelengths of electromagneticradiation from 100 nm to 10 μm. The thickness or spacing of gap 415 canbe set by the target wavelength range for the optical Casimir cavity. Insome examples, the gap 415 of a Casimir cavity can have a spacing offrom 10 nm to 2 μm.

The reflector material for first reflector 405 and/or second reflector410 can be chosen based upon its reflectivity over the wavelength rangeof interest, ease of deposition, and/or other considerations, such ascost. The reflector thickness must be sufficient to provide adequatereflectivity, but not so thick as to be difficult to pattern. In someexamples, a reflector can have a thickness of at least 10 nm, such asfrom 10 nm to 1 cm. Example materials useful as a reflector of anoptical Casimir cavity include, but are not limited to, metals,dielectric reflectors, or diffractive reflectors, such as Braggreflectors or metamaterial reflectors. Example metals useful for areflector of an optical Casimir cavity include, but are not limited to,Al, Ag, Au, Cu, Pd, or Pt. Example dielectrics useful for a dielectricreflector include, but are not limited to ZrO₂, SiO₂, Si₃N₄, Nb₂O₅,TiO₂, MgF₂, LiF, Na₃AlF₆, Ta₂O₅, LaTiO₃, HfO₂, ZnS, ZnSe, or the like.Example reflectivity for at least one of the two reflectors of anoptical Casimir cavity is from 50% to 100% for at least some wavelengthsof electromagnetic radiation from 100 nm to 10 μm. The reflectors of anoptical Casimir cavity do not have to be metals or dielectricreflectors, and instead a reflective interface may be used. For example,the reflective layer can be a step in the index of refraction at aninterface between two adjacent materials, such as between the cavitylayer and its surrounding material. In some cases the cavity walls canprovide a step in dielectric constant or index of refraction ontransitioning from one dielectric material to another one or more, orbetween a dielectric material and free space.

Alternatively, an optical Casimir cavity may be formed from adistributed Bragg reflector type multilayer dielectric stack. Forexample such a stack can comprise alternating layers of two or moredielectric materials having different indices of refraction. For thecase of two types of materials, the thickness of each pair of layerscharacterizes the pitch. Wavelengths of twice the pitch are reflected,and longer wavelengths are largely suppressed. It is to be noted thatthis differs from antireflection coatings, in which the pitch is onequarter of a wavelength rather than one half of a wavelength, which isthe case here. The layer thicknesses may further be chirped to enhancethe spectral width of the reflections. Any suitable number ofalternating dielectric layers of can be used, such as from 2 layers to100 layers, or more.

In FIG. 4, a transport medium 450 is positioned adjacent to the opticalCasimir cavity 400 such that one side of the transport medium 450 facesthe optical Casimir cavity 400, establishing an asymmetry. Transportmedium 450 can comprise a material that permits transmission of chargecarriers, which can be used in a process of product generation via thedifference in zero-point energy densities established by the presence ofthe optical Casimir cavity 400.

In the systems described herein that employ optical Casimir cavities,the charge carriers that are excited can be used directly to generateproducts, such as chemical reaction products or light emission. To makeuse of or capture energy in the form of charge carrier excitation, thecharge carrier will need to be transported away from the point at whichit is launched and captured. Transport and capture of the charge carriermay need to be performed on very fast (i.e., short) time scales. Forexample, the transport and/or capture may occur in a time interval ofless than or about 1 ps, less than or about 100 fs, less than or about10 fs, less than or about 1 fs, or less than or about 0.1 fs. In somecases, the longer the time is, the smaller the fraction of energyavailable will be captured. Description of the need for fast transportand capture of charge carriers is described in further detail below.

Casimir Photoinjector. Photons impinging on the surface of a conductorcan cause charge carriers, usually electrons, in the conductor to becomephotoexcited, producing hot carriers. If the conductor layer issufficiently thin, then these hot carriers can traverse the conductorlayer and enter the material on the other side of it. This process iscalled internal photoemission, and also photoinjection. When this thinconductor layer is adjacent to a thin insulator, herein called atransport medium or transport layer, which is adjacent to a secondconductor layer, the hot carriers can traverse the transport layer andenter the second conductor. Although carriers may also be excitedthermally, this is not treated in the present description because itgenerally produces no net current or generation of products for thedevices described.

An example of a device that can make use of a difference in the flux ofphotoexcited charge carriers in two directions for directly generatingproducts, such as driving a chemical reaction or generating light, is aCasimir photoinjector. A cross-sectional illustration of an exampleCasimir photoinjector is provided in FIG. 5. The Casimir photoinjectorin FIG. 5 comprises a Casimir cavity 500 disposed adjacent to orcontiguous with a product generating device 550. Casimir cavity 500comprises a first reflector 505, a second reflector 510, and a gap 515,which may optionally be filled with a material, as described above.Product generating device 550 comprises a first conductive layer 555, asecond conductive layer 560, and a transport layer 565 between the firstconductive layer 555 and the second conductive layer 560. In such aconfiguration, first conductive layer 555 can function, at least inpart, as the second reflector 510 of Casimir cavity 500.

Example materials for the first conductive layer 555 and/or the secondconductive layer 560, include, but are not limited to metals,semiconductors (e.g., low band-gap semiconductors), two-dimensionalconductive materials, and conductive ceramics. In some cases, the secondconductive layer 560 may optionally comprise an electrolyte, such as anaqueous electrolyte. Example materials for transport layer 565, include,but are not limited to, dielectrics, some semiconductors, andelectrolytes, such as aqueous electrolytes. Example aqueous electrolytesinclude sodium and lithium salt solutions, base electrolytes such as aKOH, NaOH, and B₄K₂O₇ solutions, and acid solutions such as H₂SO₄. Solidpolymer electrolytes can also be used, such as Nafion.

In first conductive layer 555, there are at least two ways to excite thecarriers into the hot carrier state. One is from photons impinging onthe outer surface of the conductor, producing photoexcited carriers asdescribed above. Ignoring thermally generated (blackbody) photons, asource of photons that can produce photoexcited carriers is the ambientquantum vacuum modes. Another non-thermal way to excite the carriers isfrom the internal zero-point energy fluctuations in the material of thefirst conductive layer 555. The combination of these two methodsproduces hot carriers that can enter the transport layer 565.

In the second conductive layer 560, a similar situation exists exceptthat the second conductive layer 560 is too thick to allow photoexcitedcarriers produced on the outer surface of the conductor to penetrate thesecond conductive layer 560 and reach the transport layer 565. Insteadthe photoexcited carriers are scattered in the second conductive layer560 and lose their excess energy, such as in the form of phonons andplasmons. Therefore, in the second conductive layer 560, the onlynon-thermal excitation source for hot carriers is from the internalzero-point energy fluctuations in the material of the second conductivelayer 560. Because the second conductive layer 560 is thicker than thefirst conductive layer 555, the overall internal generation rate ofexcited carriers that are available to traverse the transport layer 565is greater than that in the thinner first conductive layer 555.

Under equilibrium conditions, the carrier current from the secondconductive layer 560 must be exactly the same as the carrier currentproduced in the first conductive layer 555 from the combination ofinternal and external energy sources. The current of carriers from thefirst conductive layer 555 to the second conductive layer 560 isprecisely balanced by the current of carriers from the second conductivelayer to the first conductive layer under equilibrium conditions.

On the other hand, with Casimir cavity 500 covering the first conductivelayer 555, then the flux of photons impinging on the outer surface ofthe first conductive layer 555 is reduced. Hence, the generation rate ofphotoexcited carriers is reduced. This upsets the balance in the currentof carriers between the two conductive layers, such that a there is anet current of carriers (e.g., electron current) from the secondconductive layer 560 to the first conductive layer 555. Because thecarriers are usually electrons, which carry a negative charge, theconventional positively-charged current flows from the first conductivelayer 555 to the second conductive layer 560. In some cases, in contrastto the illustration in FIG. 5, another Casimir cavity may be positionedadjacent to second conductive layer, which can have a different criticaldimension (i.e., gap) from that of Casimir cavity 500, to provide animbalance in the current of carriers between the two conductive layers555 and 560.

The Casimir photoinjector is a DC (direct current) device, in whichdiffering average currents originating from first conductive layer 555and second conductive layer 560 produce a voltage between firstconductive layer 555 and second conductive layer 560. This voltage oraverage difference in currents can be exploited for driving chemicalreactions at product generating device 550 configured as a chemicalreaction device. The flow of charge carriers through the transport layercan also or alternatively be used for generation of light at productgenerating device 550 configured as a light emission device. Theseaspects are each described in further detail below.

Regarding the time interval for how quickly energy from the zero-pointfluctuations must be extracted before it is returned to its source or iscancelled by an opposite-energy pulse, and becomes unavailable, thistime interval may be governed by a tradeoff in the amount of energy thatis available to be extracted from the vacuum, ΔE, and time interval thatis available for extraction, Δt. This results in a ΔFΔt≤constant so thatthe larger the energy to be extracted, the shorter the time that it isavailable. If that constant is equal to h/2, where h is Planck'sconstant divided by 2π, then, based on this relationship, harvesting theenergy of a photon of 2 eV (ΔE), would indicate that Δt≤0.16 fs. Sincehot electron transport across a thin insulating layer can occur in timesthat approach 1 fs, under this condition the transport process can beused to extract at least a fraction of the zero-point energy-excitedcharge carriers.

Other structures that support charge transport from internalphotoemission can be used as Casimir photoinjectors in place of theconductor/transport layer/conductor arrangement described above. Theseinclude Schottky diodes, and metal/insulator/semiconductor (MIS) diodes,Mott diodes, quantum well diodes, ballistic diodes, carbon nanotubediodes, superconductor/insulator/superconductor (SIS) devices, and otherstructures that facilitate the injection of charge as known to thoseskilled in the art.

The transport distance, and hence transport time, for a Schottky-diodecan be larger than for the case of the conductor/transportlayer/conductor structures described herein. Because of the longertransport time, the fraction of hot carriers that are captured andcollected can be diminished. A shorter accumulation or depletion widthmay result in a quicker capture time. To reduce the width of theaccumulation or depletion layer, the semiconductor may be doped heavily,for example, such as with a dopant concentration of from 10¹⁵ cm⁻³ to10²¹ cm⁻³, or a subrange thereof. In some cases, a thin semiconductorregion between conductive layers, which is a variation on a Schottkybarrier called a thin Mott barrier, can be used to reduce the transportdistance. Both of these methods of reducing the transport distance canreduce the transport time and hence increase the fraction of hotcarriers that are captured and collected.

Plasmon Casimir cavities. In contrast to an optical Casimir cavity,where zero-point energy electromagnetic oscillations in vacuum ortransparent media are suppressed, a cavity in which zero-point energyplasmon oscillations are suppressed is referred to herein as a plasmonCasimir cavity.

A plasmon Casimir cavity can be formed by structuring a conductivemedium in a way that limits the zero-point energy plasmon modes that aresupported by the medium. This can be accomplished, for example, byincorporating a periodic structure having a pitch that suppresses a bandof zero-point energy plasmons. Plasmon wavelengths of twice the pitchare reflected, and longer wavelengths are largely suppressed. Thisresults in the full spectrum of zero-point energy modes exterior to theplasmon Casimir cavity being larger and more numerous than theconstrained set of modes in the interior, and thus there is a lowerenergy density in the interior.

One way to produce such a periodic structure is with use of adistributed Bragg reflector. Such a reflector can be formed usingmetamaterials, metasurfaces, or multilayer stacks of differentconductors, and can suppress a range of plasmonic modes in a conductor,similar to the way that an optical Casimir cavity suppresses a range ofelectromagnetic modes. The plasmon Casimir cavity can be used inspecific structures to provide an asymmetry in zero-point energydensity, as described below.

FIG. 6 provides an illustration of an example plasmon Casimir cavity 600including a distributed Bragg reflector type multilayer stack. PlasmonCasimir cavity 600 is analogous to a dielectric stack reflector that isused to form an optical mirror, but is instead formed from layers ofconductors 621 and 622 to form a plasmon reflector, which can be used tosuppress plasmon modes in the vertical direction, as shown by arrow 630.The configuration shown in FIG. 6 incorporates at least two types ofconductors 621 and 622 that differ in their plasmonic properties, suchas free electron density, electron mass, electron mobility, Fermi levelor morphology. At high frequencies where the conductors becometransparent, usually in the ultraviolet, the two types of conductorsdiffer in index of refraction. Conductors 621 and 622 are formed as analternating stack in which the thickness of each pair of layerscharacterizes the pitch. Plasmon wavelengths of twice the pitch arereflected, and longer wavelengths are largely suppressed. The layerthicknesses may further be chirped to enhance the spectral width of thereflections. Optionally, a very thin dielectric or semiconductor (e.g.,comprising SiO₂, Al₂O₃, NiO, Nb₂O₅, Ta₂O₅, CrO, a-Si:H (hydrogenatedamorphous silicon), or TiO₂), such as having a thickness between 0.2 and20 nm, can substitute for an individual layer of conductor 621 or 622 orcan be incorporated into an individual layer of conductor 621 or 622 tosupplement the plasmon reflection characteristics. The suppressionresults in the full spectrum of zero-point energy modes exterior to theplasmon Casimir cavity being larger and more numerous than theconstrained set of modes in the interior, and thus there is a lowerenergy density in the interior. One example is alternating conductorlayers of Ag (electron density of 6×10²² cm⁻²) and Al (electron densityof 18×10²² cm⁻²) in which each layer is 50 nm thick, to provide a pitchof 100 nm. If each pair of alternating layers is 100 nm thick, ten pairsof such alternating layers would be 1 μm thick. Any suitable number ofalternating layers of conductors 621 and 622 can be used, such as from 2layers to 100 layers, or more. As an example, FIG. 6 shows 3 pairs. Itwill be appreciated that other multilayer structures incorporatingconductors known to those skilled in the art may also be used torestrict the plasmon spectrum and provide a plasmon Casimir cavity.

Since plasmon Casimir cavities can suppress a range of plasmon modes,they can provide the sort of asymmetry needed for zero-point energyharvesting. To harvest or capture energy in the form of a chargecarrier, the charge carrier will need to be transported away from thepoint at which it is launched and captured. Transport and capture of thecharge carrier may need to performed at very fast time scales. Forexample, the transport and/or capture may occur in a time interval ofless than or about 1 ps, less than or about 100 fs, less than or about10 fs, less than or about 1 fs, or less than or about 0.1 fs. In somecases, the longer the time is, the smaller the fraction of energyavailable will be captured. Description of fast transport and capture ofcharge carriers generated using plasmon Casimir Cavities is described infurther detail below.

Plasmon injector. Plasmons within a conductor can transfer energy tocharge carriers in the conductor so that they become excited, producinghot carriers. When the conductor is adjacent to a thin transport layer,which is adjacent to a second conductor, the hot carriers can traversethe transport layer and enter the second conductor. In addition,plasmons can induce carrier tunneling through a transport layer.

An example of a device that can make use of a difference in the flux ofplasmon excited charge carriers in two directions for harvesting energyor direct generation of products is a plasmon injector. Across-sectional illustration of an example plasmon injector is providedin FIG. 7. The plasmon injector in FIG. 7 comprises aconductor/transport layer/conductor device including a plasmon Casimircavity 700 as the first conductor 720, a transport layer 750 adjacent toand in contact with plasmon Casimir cavity 700, and a second conductor730 adjacent to and in contact with transport layer 750. Transport layer750 is positioned between the plasmon Casimir cavity 700 and the secondconductor 730. Plasmon Casimir cavity 700 is depicted in FIG. 7 as amultilayer conductor stack, with alternating layers of one conductor 721and another conductor 722, but can also be formed with other structuresthat restrict the plasmon spectrum. Transport layer 750 and secondconductor 730 can comprise portions of a product generating device.

The orientation of plasmon Casimir cavity 700, second conductor 730, andtransport layer 750 shown in FIG. 7 is not intended to be limiting, butmay correspond to one way for orienting these components relative to asupporting dielectric and may allow for a simplified fabrication, insome embodiments. Alternatively, the alternating conductors 721 and 722can be supported by a dielectric, which can also support the transportlayer 750 and second conductor 730 (e.g., to provide a horizontalorientation rather than the vertical orientation shown in FIG. 7).

Example materials for the conductor of the plasmon Casimir cavity, suchas conductors 721 and 722 and/or the second conductor 730, include, butare not limited to metals, superconductors, semiconductors (e.g., lowband-gap semiconductors), two-dimensional conductive materials,conductive ceramics and or other materials that support plasmons. Insome cases, the second conductor 730 may optionally comprise anelectrolyte, such as an aqueous electrolyte. Example materials fortransport layer 750, include, but are not limited to, dielectrics, somesemiconductors, and electrolytes, such as aqueous electrolytes. Exampleaqueous electrolytes include sodium and lithium salt solutions, baseelectrolytes such as a KOH, NaOH, and B₄K₂O₇ solutions, and acidsolutions such as H₂SO₄. Solid polymer electrolytes can also be used,such as Nafion.

As noted above, plasmon Casimir cavity 700 limits the plasmon spectrumtherein, but second conductor 730 has no limiting metasurface and so thefull spectrum of surface plasmon modes that the second conductor 730 cansupport are allowed. In the plasmon Casimir cavity 700, carriers can beexcited into the hot carrier state by zero-point energy-driven plasmonmodes, and these hot carriers can enter the transport layer 750, andalso carriers can tunnel from the first conductor 720 through thetransport layer 750 to the second conductor 730. In the second conductor730, a similar situation exists, where carriers can be excited into thehot carrier state by zero-point energy-driven plasmon modes, and alsocarriers can tunnel from the second conductor 730 through the transportlayer 750 to the first conductor 720. Under equilibrium conditions inthe absence of a plasmon Casimir cavity configuration, the carriercurrent from a first conductor on one side of a transport layer must beexactly the same as the carrier current from a second conductor on theopposite side of transport layer. On the other hand, with theconfiguration of a plasmon Casimir cavity 700, the supported zero-pointenergy-driven plasmon modes therein are reduced. Hence, the generationrate of hot carriers from plasmon Casimir cavity 700 is reduced, andalso the density of plasmons available to induce tunneling from firstconductor 720 is reduced. This upsets the balance in the current ofcarriers between the plasmon Casimir cavity 700 and the second conductor730, such that a there is a net current of carriers (e.g., electroncurrent) from the second conductor 730 to the first conductor 720.Because the carriers are usually electrons, which carry a negativecharge, the conventional positively-charged current flows from theplasmon Casimir cavity 700 to the second conductor 730.

The plasmon injector is a DC (direct current) device, in which differingaverage currents originating from plasmon Casimir cavity 700 and secondconductor 530 produce a voltage between them. This voltage or averagedifference in currents can be exploited for driving chemical reactionsin a chemical reaction device. The flow of charge carriers through thetransport layer can also or alternatively be used for generation oflight in a light emission device. These aspects are each described infurther detail below.

As with the optical Casimir cavities described above, the time intervalfor how quickly energy from the zero-point energy driven plasmonfluctuations must be extracted before it is returned to its source or iscancelled by an opposite-energy pulse, and becomes unavailable, may begoverned by a tradeoff in the amount of energy that is available to beextracted from the zero-point field, ΔE, and time interval that isavailable for extraction, Δt. In general, capturing more of theavailable energy may need to occur in shorter times. Time scales on theorder of 1 fs or less are desirable for extracting at least a fractionof the zero-point energy-excited charge carriers, so very thin transportlayers are generally used.

Other structures that support charge transport from plasmon generatedcarriers can be used in a plasmon injector in place of theconductor/transport layer/conductor arrangement described above. Theseinclude Schottky diodes, and metal/insulator/semiconductor (MIS) diodes,Mott diodes, quantum well diodes, carbon nanotube diodes,superconductor/insulator/superconductor (SIS) devices, and otherstructures that facilitate the injection of charge as known to thoseskilled in the art. As described above, a semiconductor in asemiconductor diode, such as a Schottky diode, may be doped to reduce anaccumulation or depletion layer width and hence reduce the transportdistance and time to increase the fraction of captured carriers.

Casimir photoinjector and plasmon injector current generation. Currentgenerated by a Casimir photoinjector or plasmon injector can be used togenerate products such as fuel or light. The current that can begenerated may depend upon the characteristics of the optical Casimircavity or the plasmon Casimir cavity and the materials and structure ofthe adjoining product generating device.

As noted above, the energy density from the quantum vacuum is providedby the temperature independent term in Eq. 1, which is

$\begin{matrix}{{\rho({hf})} = {{\frac{8\pi f^{2}}{c^{3}}\left( \frac{hf}{2} \right)} = {\frac{4\pi{hf}^{3}}{c^{3}}.}}} & {{Eq}.2}\end{matrix}$

The flux of photons (number of photons per unit area per unit frequency)is given by

$\begin{matrix}{j = {{\rho({hf})}\frac{v}{4{hf}}}} & {{Eq}.3}\end{matrix}$

where c is the arrival speed, hf is the photon energy, and ¼ is ageometrical factor for the radiation. The total flux (number of photonsper unit area) is

$\begin{matrix}{J = {{\int{jdf}} = {{\frac{\pi}{c^{2}}{\int\limits_{f_{1}}^{f_{2}}{f^{2}{df}}}} = {\frac{3\pi}{h^{3}c^{2}}\left\lbrack {\left( {hf}_{2} \right)^{3} - \left( {hf}_{1} \right)^{3}} \right\rbrack}}}} & {{Eq}.4}\end{matrix}$

where hf₁ is the highest photon energy that is suppressed by the opticalCasimir cavity, and hf₁ is lowest photon energy that provides sufficientenergy for the photoexcited electron to surmount the barrier and tunnelthrough the transport layer. This low-energy cutoff is an approximation(the cutoff is actually gradual), because the reduction with photonenergy follows an Airy function, which describes allowed cavity modes.The current that results from this flux is approximately

I=Je=2.37×10⁻⁴[(hf ₂)³−(hf ₁)³] A/μm₂  Eq. 5

where e is the elementary charge.

For the case of a Casimir cavity providing a high energy cut off of 2.6eV and an approximate low energy barrier cutoff of 1.6 eV, the resultingcurrent is 3.2 mA/μm². The actual current may be much smaller becausethe photoinjection probability, which in an actual optical Casimircavity is dependent upon the photon absorptivity in the first conductivelayer, and is not unity. With a photoinjection probability of 0.05% andan optical Casimir cavity blocking efficiency of only 25%, the resultingcurrent drops to 0.4 μA/μm². It will be appreciated that these numbersare provided for illustration purposes only and are not intended to belimiting. The actual output could be smaller or larger depending uponthe Casimir photoinjector characteristics, geometries, materials, or thelike.

In some cases, a photo- or plasmon-injection probability of 0.05% may besufficient to achieve a useable current output. If the photo- orplasmon-injection probability is increased, however, even more currentmay be available. As described above, in equilibrium and in the absenceof Casimir cavities, there is a balance of carrier currents between thetwo conductive layers. To maintain that balance, if there is an increasein the efficiency of photo- or plasmon-excited hot carriers in the firstconductive layer traversing the transport layer then there must be acompensating reduction in the generation rate of internally generatedhot carriers in the first conductive layer that can traverse thetransport layer. Because the generation rate of photo- orplasmon-excited hot carriers is suppressed by the addition of a Casimircavity, when the efficiency of photo- or plasmon-excited hot carriers inthe first conductive layer traversing the transport layer is greater,then the carrier current that is suppressed by the addition of a Casimircavity is greater. That suppression results in a greater imbalancebetween the current of carriers from the first conductive layer to thesecond conductive layer and the current of carriers from the secondconductive layer to the first conductive layer, and hence a larger netcurrent. Therefore, it may be advantageous to provide as efficient aprocess as possible for producing and/or injecting photo- orplasmon-excited hot carriers in the first conductive layer that cantraverse the transport layer.

In some cases, structures to accomplish this can be integrated into theconductive layers of the product generating device, such as plasmonicnanostructures embedded into or on a surface of one or more of theconductive layers. Plasmonic nanostructures are a class of metamaterialin which nanoscale arrangements of materials, such as metals, canprovide efficient coupling of electromagnetic radiation into thematerial and enhance hot carrier emission. Examples of plasmonicnanostructures for enhancing optical absorption are known in the art.See, e.g., Wang et al., 2011, “Plasmonic energy collection through hotcarrier extraction,” Nano Lett., 11:12, 5426-5430; Atar et al., 2013,“Plasmonically enhanced hot electron based photovoltaic device,” OpticsExpress 21:6, 7196-7201; and Clavero, 2014, “Plasmon inducedhot-electron generation at nanoparticle/metal-oxide interfaces forphotovoltaic and photocatalytic devices,” Nature Photonics, 8:2, 95-103;which are hereby incorporated by reference. Examples of plasmonicnanostructures providing enhanced hot carrier emission and injection,such as by factors of up to 25×, are known in the art. See, e.g., Knightet al., 2013, “Embedding plasmonic nanostructure diodes enhances hotelectron emission,” Nano Lett., 13:4, 1687-1692; Chalabi et al., 2014,“Hot-electron photodetection with a plasmonic nanostripe antenna,” NanoLett., 14:3, 1374-1380; and Brongersma, 2015, “Plasmon-induced hotcarrier science and technology,” Nature Nanotechnology, 10:1, 25-34,which are hereby incorporated by reference. Example plasmonicnanostructures useful with embodiments disclosed herein may include, butare not limited to, nanoparticles of a conductive material (e.g., metal)embedded into or on a surface of a conductive layer, such as over anon-conducting or insulating material on the surface of the conductivelayer, and the patterning of the surface or interface of the conductivematerial.

One advantage of using a plasmon injector is that the injectionefficiency of the zero-point energy driven plasmon excited chargecarriers into the transport layer can be higher than a comparableinjection efficiency from an optical Casimir cavity photoinjectorsystem. As described above, in an optical Casimir cavity basedphotoinjector system, photons must be absorbed in the first conductor,and there is a loss associated with this process. In contrast, in aplasmon Casimir cavity system, the plasmons are present in the firstconductor and do not need to undergo a similar absorption process toexcite charge carriers.

Chemical reaction devices. Devices for which energy harvested fromdifferences in zero-point energy densities is used to directly drive achemical reaction are referred to herein as chemical reaction devices.Chemical reaction devices may comprise or correspond to photocatalyticdevices, photoelectrolytic devices, and/or electrochemical devices, andmay include multiple electrodes where oxidation and reduction reactionstake place at a surface of the electrodes, using energy harvested fromdifference in zero-point energy densities in different regions orstructures.

Photocatalysis, in general, and photoelectrolysis of water, inparticular, can be carried out using systems similar to the Casimirphotoinjector or plasmon injector devices described above with achemical reaction device taking the place of the transport layer andsecond conductor in a Casimir photoinjector or plasmon injector. As usedherein, the terms photocatalysis, electrochemical photolysis,photoelectrolysis, light-induced water splitting, and similar terms areused interchangeably to refer to electrochemical processes that occur atan electrode, and can manifest as oxidation and reduction reactions. Inconventional systems, these processes can be mediated by absorption oflight, but the oxidation and reduction processes in the systemsdescribed herein can be driven by differences in zero-point energydensities and by the resulting charge carrier generation and transport.Photoelectrolysis has been demonstrated using short wavelength light toproduce hydrogen fuel. In a conventional photoelectrolysis cell wherethe cathode is illuminated, it uses photogenerated electrons thatcombine with hydrogen ions in the water to produce hydrogen gas. Incontrast, to use a difference in zero-point energy densities as a powersource, a Casimir cavity adjacent to such an electrode can be used, forexample, to restrict the set of quantum vacuum modes it is exposed to,and it serves as the anode or cathode.

FIG. 8 shows an example system comprising a Casimir cavity 800 and achemical reaction device, which may correspond to a Casimirphotocatalyzer. Although Casimir cavity 800 is depicted as an opticalCasimir cavity, other Casimir cavity configurations can be used, such asplasmon Casimir cavities, as described above. In the configurationshown, the chemical reaction device comprises a first electrode 805,serving as an anode, a second electrode 810, serving as a cathode, andan electrolyte 815 between first electrode 805 and second electrode 810.First electrode 805 and second electrode 810 are connected to each otherby a conductor 895 and first electrode 805 can correspond to at least aportion of Casimir cavity 800. As depicted in FIG. 8, first electrode805 can be a hybrid component that serves as both a reflector of Casimircavity 800 and as an electrode in the chemical reaction device. In termsof a plasmon Casimir cavity, first electrode 805 can be a hybridcomponent that serves as both an end conductor of a conductor stack ofCasimir cavity 800 and as an electrode in the chemical reaction device,for example. The second electrode 810 can be immersed in electrolyte815, as shown in FIG. 8, but in some configurations the electrolyte 815can be positioned just at a region between first electrode 805 andsecond electrode 810.

In the case of water as an electrolyte and water splitting as thechemical reaction, at the surface of the first electrode 805 exposed tothe electrolyte 815, comprising water balanced with acid, the followingreaction takes place:

H₂O→½O₂↑+2e ⁻+2H³⁰

Oxygen gas is produced, and electrons flow through the conductor 895 tothe second electrode 810. The H⁺ ions are transported through theelectrolyte 815 to the second electrode 810. At the surface of thesecond electrode 810 exposed to the electrolyte 815, the followingreaction takes place:

2H⁺+2e ⁻→H²↑

When the electrolyte 815 comprises water balanced with base, a similarreaction involving OH⁻ takes place. In both cases, hydrogen gas isproduced at the second electrode 810, where it can be collected to beused as a fuel.

Splitting water takes a minimum of 1.23 eV of energy and substantiallymore to drive the reaction at practical rates. Therefore, usefulmaterials for the first electrode 805 should have a sufficiently highenergy bandgap, such as up to 10 eV. One example material that sufficesis SiC, with a bandgap of between 2.36 and 3.05 eV. Conventionalphotocatalysis has been demonstrated with a SiC photocathode. Forproduction of hydrogen from harvesting differences in zero-point energydifference, SiC may be used as the first electrode 805 adjacent to theCasimir cavity 800. For an optical Casimir cavity, the Casimir cavity800 must suppress optical modes of energy greater than that of thebandgap, and for a plasmon Casimir cavity, plasmon modes of a similarenergy must be suppressed. For a bandgap of approximately 2.5 eV, thatcorresponds to a gap spacing in Casimir cavity 800 of less than 250 nm.

The amount of hydrogen produced can be estimated from Eq. 5. For anoptical Casimir cavity with a spacing of 100 nm, the quantum vacuummodes below roughly 6.2 eV are suppressed. For an optical Casimir cavitygap spacing of 100 nm and SiC having a bandgap energy of approximately2.5 eV, Eq. 5 gives 53 mA/(μm)².

Several factors can reduce the efficiency of hydrogen generation belowwhat the optimal 53 mA/(μm)² would provide. One factor is the quality ofthe reflectors of an optical Casimir cavity in the visible and nearultraviolet wavelength ranges, which would be close to 100% fornear-perfect reflectors. In some cases, depending upon the materialschosen, the reflectivity can be in the range of about 35% for gold toabout 92% for aluminum when used as the hybrid reflector/first electrodeside of the Casimir cavity 800, and about 5% to 50% for SiC when used asthe hybrid reflector/first electrode side of an optical Casimir cavity.The medium filling the gap in an optical Casimir cavity can also limitthe efficiency, in that an absorptive medium reduces its effectiveness.Vacuum or air can be a desirable medium, but it can be more practical tofill the cavity with a transmissive material such as an oxide orpolymer. Such media have a bandgap that restricts the photon energy tolow photon energies, and additional losses can result from absorptioneven in the transmissive part of the spectrum. Another factor is theimperfect optical absorption in the electrodes (e.g., the anode and/orcathode), which varies with wavelength and thickness. In addition tothese optical inefficiencies, there are inefficiencies in the chargetransport and hydrogen generation. One such factor is the excess energyof charge provided by the anode and/or cathode required to drive thereaction at desired rates. Electrode materials having large bandgapsthat can provide large excess energies are often expensive and unstablein water, and even if available, they require the incident photons tohave high energies, above approximately 3 eV. To obtain these highenergies, an optical Casimir cavity would have a very small gap, wellbelow 200 nm, to suppress sufficiently high energies. High energieswould also provide a greater current, as described by Eq. 5, and higherabsorption in the electrodes (e.g., the anode and/or cathode). However,high energies are also absorbed more by the optical Casimir cavity gapmedium and tend to be reflected more poorly by the optical Casimircavity reflectors. Furthermore, forming small-gap optical Casimircavities is often technologically more challenging. Otherefficiency-limiting factors include losses from resistance of theelectrodes (e.g., the anode and/or cathode), of the water, and of theconductor. It will be appreciated that the numbers identified above areprovided for illustrative purposes only and are note intended to belimiting. These values may vary greatly for different anode, cathode,and optical Casimir cavity materials, and for different cellconfigurations.

Estimating losses of a factor of 100 for the optical inefficienciesdescribed above, and an additional factor of 100 for the chargetransport and hydrogen generation process, gives an overall loss of afactor of 10⁴. This factor of 10⁴ would result in a reduction of thecurrent from 53 mA/(μm)² to 5.3 μA/(μm)². Converting that current intoH₂ production, gives a rate of approximately 28 pg/(μm)²-sec,corresponding to 0.3 g/sec for an area of 100 cm². At this rate,approximately 1 kg of H₂ would be produced in one hour over that the 100cm² area, which is sufficient to run a fuel-cell-powered vehiclecontinuously.

In some cases, parts of the system may produce heat, while otherspotentially absorb heat, resulting in cooling. The heat productionresulting from the difference between an up-to-6.2 eV photon input andthe roughly 1.5 eV required for electrolysis may limit the rate at whichfuel can be reduced. For heat-absorbing parts of the system,high-density fuel production may be limited by the rate of heat transferrequired to maintain the system temperature within operating limits,such as by application of heat or absorbing heat from the environment.An optical Casimir cavity having a larger gap spacing, to reduce thehigh photon energy input, and a cell having an area greater than 100 cm²may be useful for reducing the thermal flow per unit area.

The zero-point-energy-driven photoelectrolysis example given above isintended to be illustrative, and not limiting. There are many othermaterials and configurations for conventional photoelectrolysis that canbe used, as is known to those skilled in the art. A Casimir cavitycathode can be used instead of an Casimir cavity anode, or bothelectrodes can incorporate Casimir cavities. The cathodes or anodes canalternatively be in the form of Schottky barriers, p-n junctions,semiconductor/liquid junctions and other devices known to those skilledin the art, and these semiconductor materials may be doped to reduce anaccumulation or depletion layer width, for example. Examples of specificanode and cathode structures for solar driven water splitting systems,which can also be used in the systems described herein, are given inWalter, Michael G., et al, “Solar water splitting cells,” ChemicalReviews, 110.11 (2010): 6446-6473, which is hereby incorporated byreference. If both electrodes incorporate Casimir cavities, then theeffects can be additive, much like the case for conventionalphotoelectrolysis where the photon energy may not be sufficient forelectrolysis with a single photoelectrode but use of both a photocathodeand a photoanode can be useful for driving the photoelectrolysis. Thewater conductivity may vary depending upon the electrolyte content, andacid, base or salt electrolytes may be added. The gap between anode andcathode can be reduced to less than a Debye length, roughly 1 micron inpure water, to enhance ion transport. While the photoelectrolysisembodiment provided above is one example of zero-point-energy-drivenphotocatalysis, zero-point-energy-driven photocatalysis can be used morebroadly with other fluids to provide other useful substances.

Light emission devices. Light can be produced directly from variationsof conductor/insulator/conductor structures, such as those describedabove with respect to Casimir photoinjectors and plasmon injectors in asystem referred to herein as a Casimir light source. One example of aCasimir light source can employ use of structures exhibitingcathodoluminescence. FIG. 9A shows an example of a Casimir light sourceincorporating a light emission device 920 comprising a luminescentstructure 925 coupled to a Casimir cavity 900, which may be referred toherein as a Casimir cathodoluminescence system. In the Casimirphotoinjectors described above with respect to FIG. 5, a net flow of hotelectrons is excited from second conductive layer 560 to firstconductive layer 555. In the plasmon injectors described above withrespect to FIG. 7, a net flow of hot electrons is excited from secondconductor 730 to first conductor 720. By placing a luminescent structure925, such as a nanosheet phosphor, for example a 2.4 nm thick nanosheetor double-layered perovskite, in the transport layer adjacent to theCasimir cavity 900, or in place of the transport layer, the hotelectrons can impinge on the phosphor and produce light, such as via acathodoluminescence mechanism. Casimir cavity 900 is exemplified in FIG.9A as an optical Casimir cavity comprising a first reflective layer 905and a second reflective layer 910, which can serve as a hybrid layer,providing the first conductor in the light emission device 920. Otherconfigurations can be used for Casimir cavity 900, such as a plasmonCasimir cavity, where the end conductor of a conductor stack of Casimircavity 900 serves as a hybrid layer, providing the first conductor inthe light emission device 920, for example.

Light can also be emitted by applying a voltage across aconductor/insulator/conductor tunneling junction to produce inelastictunneling that excites surface plasmon modes that produce radiation.This can be seen, for example, in a Al/Al₂O₃/Au device. FIG. 9B shows anexample of a Casimir light source incorporating a light emission devicecomprising an inelastic tunneling structure 921 coupled to a Casimircavity 901. Such a system can be similar to the photoinjectors orplasmon injectors described above, where the inelastic tunnelingstructure 921 replaces a conductor/insulator/conductor structure,allowing light to be directly produced. In the configuration shown,plasmons can be formed on either or both of the electrodes of inelastictunneling structure 921. The effect can be enhanced by inducing surfaceplasmon modes to aid in the light emission, for example by producing theconductor insulator conductor structures on a roughened surface,schematically illustrated in FIG. 9B by structures present at the rightsurface of electrode 915. One way to produce such a roughened surface isdescribed in McCarthy, S. L., and John Lambe, “Enhancement of lightemission from metal-insulator-metal tunnel junctions,” Applied PhysicsLetters, 30.8 (1977): 427-429, which is hereby incorporated byreference. Casimir cavity 901 is again exemplified in FIG. 9B as anoptical Casimir cavity comprising a first reflective layer 905 and asecond reflective layer 910, which can serve as a hybrid layer,providing an electrode of the inelastic tunneling structure 921, butother configurations can be used for Casimir cavity 901, such as aplasmon Casimir cavity, where the end conductor of a conductor stack ofCasimir cavity 901 serves as a hybrid layer, providing an electrode ofthe inelastic tunneling structure 921, for example.

Still another way to produce light directly is using negativedifferential resistance. FIG. 9C shows an example of a systemincorporating a light emission device comprising a structure 922exhibiting negative differential resistance coupled to a Casimir cavity902. An example configuration for structure 922 can comprise a doublebarrier Al/Al₂O₃/Al/Al₂O₃/Au with 3 to 6 nm thick Al₂O₃ layers. Such astructure 922 can produce negative differential resistance at a bias ofapproximately 1 volt. By using such a double barrier structure, thecurrent and voltage induced as a result of the Casimir cavity 902 canproduce the needed power for light emission. Casimir cavity 902 isexemplified in FIG. 9C as an optical Casimir cavity comprising a firstreflective layer 905 and a second reflective layer 910, which can serveas a hybrid layer, providing the first conductor in the double barrierstructure 922. Again, although Casimir cavity 902 is exemplified in FIG.9C as an optical Casimir cavity comprising a first reflective layer 905and a second reflective layer 910, other configurations can be used forCasimir cavity 902, such as a plasmon Casimir cavity.

In each of the systems described above including a light emissiondevice, the current returns through an element 950. Element 950 can be aresistor, for example, that supports a voltage difference between twoelectrodes. Element 950 can alternatively be a short circuit, which maybe beneficial in the case of FIG. 9A, which does not need to support avoltage difference. Element 950 can also be a battery or load, whichmakes use of the power from the return current.

To make the light visible outside of the device, the systems canoptionally be formed as an array of very narrow structures, less than200 nm wide, such that the light is emitted at the edges of thestructures. Alternatively, the outermost electrode of the light emissiondevice (e.g., opposite the side adjacent to the Casimir cavity) cancomprise a transparent conductor, such as indium tin oxide (ITO), andthe light can be emitted through the transparent conductor.

Systems comprising light emission devices can be used for generalillumination, and also to couple directly to plants and chlorophyll forbiosynthesis. The appropriate wavelengths to energize chlorophyll toproduce carbohydrates are roughly between 400 nm and 700 nm,corresponding to photon energies of 3 eV to 1.7 eV, and thelight-producing devices described above can be tuned to that range usingthe relationship between an optical Casimir cavity gap width and photonenergy. The configurations described above can provide continuousillumination when desired, even in the absence of application of anexternal voltage or current.

Device arrays. To achieve large output amounts of light or fuel,multiple systems described herein can be configured into an array, suchthat the output from each individual system is integrated to provide ahigher total output from the array.

Device fabrication. An example fabrication process according to apattern 1001 shown in FIG. 10A for a Casimir cathodoluminescence system1000 as illustrated in cross-section in FIG. 10B is described below. Thedevice is formed on a glass substrate 1002, through which the light thatis produced is emitted.

Casimir cathodoluminescence system 1000 is shown comprising atransparent conductor/phosphor/conductor device, which comprises atransparent conductor layer 1005, a phosphor layer 1010 (correspondingto a transport layer), and a second conductor layer 1015, adjacent to anoptical Casimir cavity. The optical Casimir cavity comprises the secondconductor layer 1015, a cavity layer 1020, and a reflective layer 1025.Pattern 1001 includes a transport/phosphor layer pattern 1011 and asecond conductor layer/Casimir cavity pattern 1021. The optical Casimircavity restricts quantum vacuum energy modes on one side of a lightgenerating device comprising second conductor layer 1015, phosphor layer1010, and transparent conductor layer 1005.

In an example, a cell comprising a Casimir cathodoluminescence system1000 may have an active area of 100 μm×100 μm. The Casimircathodoluminescence system 1000 can be adjacent to other Casimircathodoluminescence systems to form an array.

Transparent conductor layer. The transparent conductor layer 1005,composed of indium tin oxide (ITO), forms the base layer for the Casimircathodoluminescence system 1000. It coats the entire glass substrate andis not patterned. By way of example, the following steps can be used forpreparation of the transparent conductor layer 1005:

1. ITO is sputtered onto the glass substrate from a ceramic In₂O₃—SnO₂target in a gas of argon with a small quantity of oxygen, to a thicknessof 200 nm.

Transport and phosphor layers. Hot electrons generated in thetransparent conductor layer 1005 are injected into and excite lightemission in the phosphor layer 1010. In this example the transport layerconsists solely of the phosphor layer 1010. As described above, however,the phosphor layer 1010 can optionally comprise a sublayer of thetransport layer. By way of example, the following steps can be used forpreparation of the phosphor layer 1010:

1. Negative photoresist is spun onto the ITO-coated substrate 1002 andsoft baked.2. Using an aligner, the transport/phosphor layer pattern 1011 shown inFIG. 10A is exposed, followed by a post-exposure bake, develop andrinse.3. The phosphor is then applied onto the surface. It comprises anexfoliated sheet of double-layered perovskite, NaGdMgWO6:Eu³⁺, which isprepared as described in Viswanath, N. S. M., et al. “A nanosheetphosphor of double-layered perovskite with unusual intrananosheet siteactivator concentration,” Chemical Engineering Journal, 2019, 122044,which is herein incorporated by reference. It is 2.4 nm thick.4. The phosphor is lifted off with acetone, followed by isopropanol andthen a water rinse, to form the phosphor layer 1010.5. The remaining photoresist is cleaned off with a brief oxygen plasma.

Second conductor layer, Casimir cavity transparent layer and mirror.Second conductor layer 1015 forms the upper conductive layer, absorbingphotons from the optical Casimir cavity to produce hot electrons, andmakes contact with the phosphor layer 1010 and also with the transparentconductor layer 1005. This contact forms, for example, the element 950shown in FIG. 9C. These layers are deposited and then patternedtogether. By way of example, the following steps can be used forpreparation of the second conductor layer 1015, cavity layer 1020, andreflective layer 1025:

1. 15 nm of palladium is evaporated onto the substrate to form secondconductor layer 1015.2. 30 nm of SiO₂ is deposited by sputtering onto the substrate for useas a cavity layer 1020, followed by 150 nm of aluminum for use asreflective layer 1025.3. Positive photoresist is spun onto the substrate and soft baked.4. Using an aligner, the field for the second conductor layer/Casimircavity pattern 1021 is exposed, followed by a post-exposure bake,develop and rinse.5. The exposed aluminum and SiO₂ are etched with 6:1 buffered oxide etch(BOE), followed by a water rinse, to form the reflective layer 1025 andcavity layer 1020 of the optical Casimir cavity.6. The exposed palladium is etched with a CF₄—Ar plasma to completepatterning of second conductor layer 1015.5. The remaining photoresist is cleaned off with an oxygen plasma.

It will be appreciated that the above description of a fabricationscheme for making a Casimir cathodoluminescence system 1000 is merelyexemplary and that a variety of different dimensions, processingschemes, materials, patterns, or the like may be used by the skilledartisan to prepare Casimir cathodoluminescence systems.

Example ranges of dimensions. Although a cell size of 100 μm×100 μm isdescribed above, other cell sizes can be used. Example cell sizes may befrom 0.1 μm on an edge up to 1 meter. In some examples, the chosen sizecan be determined by (i) the desired resistance of the element so as notto create too large a voltage drop between the transparent conductor andthe second conducting layer, (ii) a sufficiently small pattern arrayedto provide uniform illumination over a given area, and (iii) the ease offabrication.

Regarding ease of fabrication, smaller cells may require more expensiveor complex fabrication. For example, large area devices having featuresizes of at least 1 mm can be patterned by inexpensive screen printing,whereas submicron features may require very expensive deep-UVlithography. There are exceptions, however. For example, nanoimprintlithography can produce some types of submicron features inexpensively,and roll-to-roll manufacturing can produce small features cheaply overlarge areas. Still, usually larger features can be easier tomanufacture.

The transparent conducting layer (e.g., ITO) may be sufficiently thickto provide low sheet resistance (e.g., greater than 50 nm), but thinenough that it does not create substantial optical absorption for theemitted light.

The transport layer may be sufficiently thin to allow a large injectedelectron current through both the transport and the phosphor layers, butthick enough to facilitate hot electron emission. In the given exampleabove, the phosphor layer provides this function.

The thickness of second conductive layer can be important for producinghigh currents and therefore bright illumination. There is a tradeoffbetween films that are too thin to absorb light from the optical Casimircavity and too thick to provide injected electrons. If the secondconductive layer is too thin, it can absorb too little of the incomingphoton flux from the optical Casimir cavity. In the case of the secondconductive layer being extremely thin, its sheet conductance will be toosmall and will limit the available current. If the second conductivelayer is too thick, then hot electrons generated at the optical Casimircavity interface may not be able to reach the transport/phosphor layerbefore being scattered. For example, the ballistic mean-free path lengthin gold is 38 nm, and it is lower in palladium. In some examples, thesecond conductive layer thickness can fall in the range of 5 nm to 50nm. For metals patterned to make use of plasmonic effects describedelsewhere in the specification, the metals can be thicker, and for otherthin film materials, such as graphene and molybdenum disulfide, thematerials can be as thin as a single monolayer.

Another function of the second conductive layer is to provide adequatesheet conductance to carry the current to the transparent conductinglayer.

Illustrative Aspects

As used below, any reference to a series of aspects (e.g., “Aspects1-4”) or non-enumerated group of aspects (e.g., “any previous orsubsequent aspect”) is to be understood as a reference to each of thoseaspects disjunctively (e.g., “Aspects 1-4” is to be understood as“Aspects 1, 2, 3, or 4”).

Aspect 1 is a system comprising: a product generating device; and azero-point-energy-density-reducing structure adjoining the productgenerating device, the zero-point-energy-density-reducing structureproviding an asymmetry with respect to the product generating devicethat drives a flow of energy through the product generating device.

Aspect 2 is the system of any previous or subsequent aspect, wherein theflow of energy occurs even in an absence of external sources ofillumination.

Aspect 3 is the system of any previous or subsequent aspect, wherein theflow of energy occurs even in an absence of application of voltage orcurrent to the product generating device from an external source.

Aspect 4 is the system of any previous or subsequent aspect, wherein thezero-point-energy-density-reducing structure comprises a Casimir cavity.

Aspect 5 is the system of any previous or subsequent aspect, wherein thezero-point-energy-density-reducing structure comprises an opticalCasimir cavity.

Aspect 6 is the system of any previous or subsequent aspect, wherein thezero-point-energy-density-reducing structure comprises a plasmon Casimircavity.

Aspect 7 is the system of any previous or subsequent aspect, wherein theproduct generating device comprises a chemical reaction device driven bythe flow of energy.

Aspect 8 is the system of any previous or subsequent aspect, wherein theproduct generating device comprises a fuel production device.

Aspect 9 is the system of any previous or subsequent aspect, wherein theproduct generating device comprises an electrolysis device.

Aspect 10 is the system of any previous or subsequent aspect, whereinthe product generating device comprises a photocatalysis device.

Aspect 11 is the system of any previous or subsequent aspect, whereinthe product generating device comprises: a first electrode adjoining thezero-point-energy-density-reducing structure; a second electrode inelectrical communication with the first electrode; and an electrolytebetween the first electrode and the second electrode.

Aspect 12 is the system of any previous or subsequent aspect, whereinthe first electrode comprises a semiconductor having a band gap from1.23 eV to 10 eV.

Aspect 13 is the system of any previous or subsequent aspect, operablefor electrolysis of water.

Aspect 14 is the system of any previous or subsequent aspect, whereinthe first electrode comprises SiC.

Aspect 15 is the system of any previous or subsequent aspect, whereinthe electrolyte comprises water.

Aspect 16 is the system of any previous or subsequent aspect, whereinthe first electrode comprises a reflective layer of thezero-point-energy-density-reducing structure.

Aspect 17 is the system of any previous or subsequent aspect, whereinthe first electrode comprises a structured conductor of thezero-point-energy-density-reducing structure.

Aspect 18 is the system of any previous or subsequent aspect, whereinthe product generating device comprises a light emission device drivenby the flow of energy.

Aspect 19 is the system of any previous or subsequent aspect, whereinthe light emission device comprises: a first conductive layer adjoiningthe zero-point-energy-density-reducing structure; a transport layeradjacent to the first conductive layer; and a second conductive layeradjacent to the transport layer.

Aspect 20 is the system of any previous or subsequent aspect, whereinthe second conductive layer comprises a transparent conductor.

Aspect 21 is the system of any previous or subsequent aspect, whereinthe first conductive layer comprises a reflective layer of thezero-point-energy-density-reducing structure.

Aspect 22 is the system of any previous or subsequent aspect, whereinthe first conductive layer comprises a structured conductor of thezero-point-energy-density-reducing structure.

Aspect 23 is the system of any previous or subsequent aspect, whereinthe light emission device comprises a phosphor positioned adjacent tothe zero-point-energy-density-reducing structure.

Aspect 24 is the system of any previous or subsequent aspect, whereinthe light emission device comprises a cathodoluminescent structure.

Aspect 25 is the system of any previous or subsequent aspect, whereinthe light emission device comprises a perovskite nanosheet phosphorpositioned adjacent to the zero-point-energy-density-reducing structure.

Aspect 26 is the system of any previous or subsequent aspect, whereinthe light emission device comprises a plasmon-driven light emissiondevice.

Aspect 27 is the system of any previous or subsequent aspect, whereinthe light emission device comprises an conductor/insulator/conductortunneling junction.

Aspect 28 is the system of any previous or subsequent aspect, wherein atleast one conductor includes a metasurface.

Aspect 29 is the system of any previous or subsequent aspect, wherein atleast one conductor includes a structural discontinuity.

Aspect 30 is the system of any previous or subsequent aspect, whereinthe light emission device exhibits a negative differential resistance.

Aspect 31 is the system of any previous or subsequent aspect, whereinthe light emission device comprises a double barrier junction.

Aspect 32 is the system of any previous or subsequent aspect, whereinthe light emission device comprises aconductor/insulator/conductor/insulator/conductor structure.

Aspect 33 is the system of any previous or subsequent aspect, whereinthe light emission device emits light having at least some wavelengthsfrom 400 nm to 700 nm.

Aspect 34 is the system of any previous or subsequent aspect, whereinthe Casimir cavity comprises: a first reflective layer; a cavity layer;and a second reflective layer, wherein the cavity layer is between thefirst reflective layer and the second reflective layer.

Aspect 35 is the system of any previous or subsequent aspect, whereinthe cavity layer comprises a condensed-phase optically transparentmaterial layer.

Aspect 36 is the system of any previous or subsequent aspect, whereinthe cavity layer comprises a material having a transmittance of greaterthan 20% for at least some wavelengths of electromagnetic radiation from100 nm to 10 μm.

Aspect 37 is the system of any previous or subsequent aspect, wherein areflectivity of at least one of the first reflective layer or the secondreflective layer is greater than 50%.

Aspect 38 is the system of any previous or subsequent aspect, whereinthe second reflective layer comprises a conductive layer of the productgenerating device.

Aspect 39 is the system of any previous or subsequent aspect, whereinthe Casimir cavity comprises: a conductor structured to limit a range ofzero-point energy plasmon modes within the conductor.

Aspect 40 is the system of any previous or subsequent aspect, whereinthe conductor comprises a component of the product generating device.

Aspect 41 is the system of any previous or subsequent aspect, whereinthe conductor comprises a series of alternating sublayers of at leasttwo different conductors.

Aspect 42 is the system of any previous or subsequent aspect, whereinthe alternating sublayers independently have thicknesses of from 0.3 nmto 1 μm.

Aspect 43 is the system of any previous aspect, wherein a dielectric ora semiconductor comprises at least a part of one sublayer.

REFERENCES

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STATEMENTS REGARDING INCORPORATION BY REFERENCE AND VARIATIONS

All references throughout this application, for example patent documentsincluding issued or granted patents or equivalents, patent applicationpublications, and non-patent literature documents or other sourcematerial, are hereby incorporated by reference herein, as thoughindividually incorporated by reference.

All patents and publications mentioned in the specification areindicative of the levels of skill of those skilled in the art to whichthe invention pertains. References cited herein are incorporated byreference herein to indicate the state of the art, in some cases as oftheir filing date, and it is intended that this information can beemployed herein, if needed, to exclude (for example, to disclaim)specific embodiments that are in the prior art.

When a group of substituents is disclosed herein, it is understood thatall individual members of those groups and all subgroups and classesthat can be formed using the substituents are disclosed separately. Whena Markush group or other grouping is used herein, all individual membersof the group and all combinations and subcombinations possible of thegroup are intended to be individually included in the disclosure. Asused herein, “and/or” means that one, all, or any combination of itemsin a list separated by “and/or” are included in the list; for example“1, 2 and/or 3” is equivalent to “‘1’ or ‘2’ or ‘3’ or ‘1 and 2’ or ‘1and 3’ or ‘2 and 3’ or ‘1, 2 and 3’”.

Every formulation or combination of components described or exemplifiedcan be used to practice the invention, unless otherwise stated. Specificnames of materials are intended to be exemplary, as it is known that oneof ordinary skill in the art can name the same material differently. Itwill be appreciated that methods, device elements, starting materials,and synthetic methods other than those specifically exemplified can beemployed in the practice of the invention without resorting to undueexperimentation. All art-known functional equivalents, of any suchmethods, device elements, starting materials, and synthetic methods areintended to be included in this invention. Whenever a range is given inthe specification, for example, a temperature range, a time range, or acomposition range, all intermediate ranges and subranges, as well as allindividual values included in the ranges given are intended to beincluded in the disclosure.

As used herein, “comprising” is synonymous with “including,”“containing,” or “characterized by,” and is inclusive or open-ended anddoes not exclude additional, unrecited elements or method steps. As usedherein, “consisting of” excludes any element, step, or ingredient notspecified in the claim element. As used herein, “consisting essentiallyof” does not exclude materials or steps that do not materially affectthe basic and novel characteristics of the claim. Any recitation hereinof the term “comprising”, particularly in a description of components ofa composition or in a description of elements of a device, is understoodto encompass those compositions and methods consisting essentially ofand consisting of the recited components or elements. The inventionillustratively described herein suitably may be practiced in the absenceof any element or elements, limitation or limitations which is notspecifically disclosed herein.

The terms and expressions which have been employed are used as terms ofdescription and not of limitation, and there is no intention in the useof such terms and expressions of excluding any equivalents of thefeatures shown and described or portions thereof, but it is recognizedthat various modifications are possible within the scope of theinvention claimed. Thus, it should be understood that although thepresent invention has been specifically disclosed by preferredembodiments and optional features, modification and variation of theconcepts herein disclosed may be resorted to by those skilled in theart, and that such modifications and variations are considered to bewithin the scope of this invention as defined by the appended claims.

What is claimed is:
 1. A system comprising: a device; and azero-point-energy-density-modifying structure adjoining the device, thezero-point-energy-density-modifying structure providing an asymmetrywith respect to the device that drives a flow of energy through thedevice.
 2. The system of claim 1, wherein thezero-point-energy-density-modifying structure is a firstzero-point-energy-density-modifying structure, the system furthercomprising: a second zero-point-energy-density-modifying structureadjoining the device, the device positioned between the firstzero-point-energy-density-modifying structure and the secondzero-point-energy-density-modifying structure, and wherein the firstzero-point-energy-density-modifying structure and the secondzero-point-energy-density-modifying structure have different geometriesor comprise different materials.
 3. The system of claim 1, wherein thezero-point-energy-density-modifying structure comprises a Casimircavity.
 4. The system of claim 3, wherein the Casimir cavity is anoptical Casimir cavity.
 5. The system of claim 3, wherein a cavity layerof the Casimir cavity comprises a solid, a liquid, a liquid crystal, ora conducting medium.
 6. The system of claim 3, wherein the Casimircavity is a plasmon Casimir cavity.
 7. The system of claim 3, wherein acavity layer of the Casimir cavity comprises a multilayer conductorstack.
 8. The system of claim 1, wherein the device is a productgenerating device.
 9. The system of claim 8, wherein the productgenerating device comprises a fuel production device.
 10. The system ofclaim 9, wherein the fuel production device is a hydrogen productiondevice.
 11. The system of claim 8, wherein the fuel production device isan electrolysis device or a photocatalysis device.
 12. The system ofclaim 1, wherein the device is an electronic device.
 13. The system ofclaim 12, wherein the electronic device comprises: a first conductivelayer comprising a component of the zero-point-energy-density-modifyingstructure; a transport layer disposed adjacent to and in contact withthe first conductive layer; and a second conductive layer disposedadjacent to and in contact with the transport layer.
 14. The system ofclaim 12, wherein the electronic device is a diode or a resistor. 15.The system of claim 12, wherein the electronic device is a lightemission device comprising a phosphor.
 16. A method comprising:providing a system comprising: a device; and azero-point-energy-density-modifying structure adjoining the device, thezero-point-energy-density-modifying structure providing an asymmetrywith respect to the device that drives a flow of energy through thedevice; and positioning an product-generating medium adjoining, adjacentto, or in contact with the device to generate products by way of theflow of energy through the device.
 17. The method of claim 16, whereinthe product-generating medium comprises a phosphor and wherein theproducts comprise photons.
 18. The method of claim 16, wherein theproduct-generating medium comprises an electrolyte and wherein theproducts comprise a gas.
 19. The method of claim 18, wherein theproduct-generating medium comprises an aqueous electrolyte and whereinthe products comprise oxygen gas and/or hydrogen gas.
 20. The method ofclaim 16, wherein the flow of energy corresponds to hot electronsgenerated at or captured in the device and wherein theproduct-generating medium receives the hot electrons or energyassociated with the hot electrons to generate the products.